The invention relates to a process for the ablative pyrolysis of biomass by means of a heating element and by means for feeding the biomass as well as to a plant therefor and to a fuel produced according to the invention.
Pyrolysis denotes a process, wherein organic material is decomposed, mostly in the absence of oxygen, into gaseous, liquid and solid decomposition products at temperatures of up to approximately 600° C. The object is to maximise the liquid decomposition products which may be used in a variety of manners as a pyrolysate having a high energy content. Flash-pyrolysis is particularly suitable for the technical conversion. The organic material to be decomposed is heated in the shortest possible time to temperatures of about 450° C. to 500° C. and the pyrolysis products formed are for the most part condensed into a pyrolysate.
Processes operating according to the principle of flash-pyrolysis use e.g. sand bed reactors, wherein finely ground particles are mixed with hot sand and are thus decomposed pyrolytically (see WO 97/06886 Biomass Technology). Other processes use heated, rotating discs against which the organic material is pressed at temperatures ranging from 500° C. to 900° C. (Martin et al., “Ablative melting of a solid cylinder perpendicularly pressed against a heated wall” in Heat Mass Transfer, Vol. 29, No. 9, pp. 1407-1415, 1986). Other methods, on the other hand, use heated, stationary reactor panels on which the organic material to be decomposed, is moved about (Bridgwater and Peacocke, Fast pyrolysis processes for biomass, in Renewable & Sustainable Energy Reviews 4, 2000, 1-73). Bridgwater and Peacocke fully describe the current state of the art for laboratory, pilot and industrial installations (to the extent that these exist). The installations described there have in common that the construction of the reactors and the processing of the pyrolysis products are relatively complicated. Furthermore, the aforesaid installations require the decomposition of the biomass into very small solids particles to ensure complete pyrolysis. The production of such fine particles is highly energy consuming and reduces the efficiency of the process.
It is an object of the invention to provide a simple process and a simple plant for the pyrolysis of organic material.